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'lua_checkstack' doesn't need to check stack overflow

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'luaD_growstack' already checks that. This commit also fixes an
internal bug in 'luaD_growstack': a large 'n' could cause an arithmetic
overflow when computing 'needed'.
This commit is contained in:
Roberto Ierusalimschy
2022-05-23 10:38:03 -03:00
parent 42d40581dd
commit 4a00f61276
5 changed files with 17 additions and 26 deletions
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15
ldo.c
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@@ -227,7 +227,7 @@ int luaD_growstack (lua_State *L, int n, int raiseerror) {
luaD_throw(L, LUA_ERRERR); /* error inside message handler */
return 0; /* if not 'raiseerror', just signal it */
}
else {
else if (n < LUAI_MAXSTACK) { /* avoids arithmetic overflows */
int newsize = 2 * size; /* tentative new size */
int needed = cast_int(L->top - L->stack) + n;
if (newsize > LUAI_MAXSTACK) /* cannot cross the limit */
@@ -236,14 +236,13 @@ int luaD_growstack (lua_State *L, int n, int raiseerror) {
newsize = needed;
if (l_likely(newsize <= LUAI_MAXSTACK))
return luaD_reallocstack(L, newsize, raiseerror);
else { /* stack overflow */
/* add extra size to be able to handle the error message */
luaD_reallocstack(L, ERRORSTACKSIZE, raiseerror);
if (raiseerror)
luaG_runerror(L, "stack overflow");
return 0;
}
}
/* else stack overflow */
/* add extra size to be able to handle the error message */
luaD_reallocstack(L, ERRORSTACKSIZE, raiseerror);
if (raiseerror)
luaG_runerror(L, "stack overflow");
return 0;
}